Study On Damage Of Surrounding Rock And Dynamic Response Characteristics Of Adjacent Caverns Under Excavation Blasting In Underground Water-sealed Oil Storage Caverns

With the development of the global economy and the tremendous changes in the international environment,energy issues have become increasingly prominent.As one of the important energy sources,oil plays an important role in the economic,political and military fields.Therefore,it is urgent to build large underground water-sealed oil storage.For large underground cavern excavation,the drilling and blasting method is still the main construction method.In the process of excavation and blasting of underground cavern group,due to the sudden release of huge energy during the explosion,it is inevitable that of explosion resource cavern remaining rock mass and adjacent cavern structure will be impacted and vibration effect will be caused.If the control is improper,the dynamic damage of cavern structure can be easily caused,which in turn adversely affects the overall stability of the underground cavern group.At present,the research results of excavation blasting technology and vibration safety control for underground water-sealed oil storage are obviously insufficient,and mainly focus on blasting scheme optimization,blasting vibration monitoring and blasting vibration prediction and control,etc.Basic theoretical studies such as dynamic response characteristics and dynamic stability are rarely involved.In addition,due to the oil storage function requirements of the underground water-sealed oil storage cavern group,the cavern structure has certain uniqueness in scale,spatial distribution and support form,which makes it difficult to promote the research results related to other underground engineering.Therefore,it is of great theoretical and practical significance to carry out in-depth study on the surrounding rock damage of underground ground oil storage depot and the dynamic response characteristics of adjacent caverns.It can improve the construction technology,guiding blasting design and vibration safety protection of underground water-sealed oil storage.In this paper,the blasting damage mechanism and dynamic response mechanism of the underground water-sealed oil storage were taken as the research core.The blasting project of the underground water-sealed oil storage in Shandong was selected as the study background.The propane storage cavern excavation blasting engineering is regarded as the study object.Based on the comprehensive method of field investigation,field test,numerical simulation and theoretical analysis,the damage of surrounding rock and the dynamic response characteristics of adjacent caverns in the underground water-sealed oil storages are studied.The main research contents and achievements include the following aspects:(1)Study on the excavation blasting vibration propagation law of underground water-sealed oil storage.On the basis of detailed field investigation and analysis of blasting scheme,field tests of blasting vibration of underground water-sealed oil storage caverns were carried out.The vibration propagation laws of the adjacent water curtain roadway and the adjacent main cavern under excavation blasting of the main cavern were obtained.The results showed that the traditional Sodev's empirical formula could be well adapted to describe the attenuation law of blasting vibration velocity for the adjacent main cavern,but for the adjacent the adjacent water curtain roadway,the Sodev's empirical formula considering elevation effect a better way to reflect the blasting vibration propagation law.(2)Study on cumulative damage effect of underground cavern surrounding rock under cyclic blasting load.By introducing the damage factor,a blasting dynamic damage analysis model was established to simulate the damage evolution process of surrounding rock under the single blasting load of underground excavation and obtain the damage distribution law of surrounding rock.To verify the reliability of the numerical,it was compared with the theoretical calculation results.On this basis,the restart technique was used to simulate the cyclic blasting process in underground caverns.The results showed that the rock damage and blasting times had a good nonlinear relation characteristic in the cyclic blasting process,and the rock mass had cumulative damage weakening effect under blasting load.The sound wave tests were carried out in the research areas of the adjacent main cavern and the water curtain roadway.The range and mechanical parameters of disturbed zone were obtained,and the depth of disturbed zone is determined to be 3.3m and 2.2m respectively.(3)Study on calculation and application of mechanical parameters of rock mass under blasting damage.On the basis of the deterioration effect of rock mass properties under the action of blasting,a new method for calculating relevant parameters based on Hoek-Brown criterion was proposed by establishing the relationship between the rock mass P-wave velocity V_P,the geological strength index GSI value and damage factor D value.Then a new improved formula for rock mass mechanical parameters was obtained.The applicability of the new improved formula was verified by the actual dam foundation rock mass engineering and slope rock mass engineering.On this basis,the mechanical strength parameters of the propane main cavern and the water curtain roadway in the research area were obtained by the new improved method in combination with the results of the laboratory rock mechanical tests and field sound wave tests.(4)Analysis and application research of blasting vibration signal based on CEEMD method.The superiority and reliability of the CEEMD method in the analysis of blasting vibration were verified from both mode confusion suppression and self-adaptive optimal algorithm index by using the simulate signal.On this basis,CEEMD method was applied to analyze the actual blasting vibration signals under excavation blasting of underground water-sealed oil storage caverns.Combined with the Hilbert transform,the time-frequency characteristics and the energy distribution law of the blasting vibration signals of the adjacent caverns were revealed.The results indicated that blasting vibration signals of the adjacent water curtain roadway and the adjacent main cavern were both characterized with more energy in high frequency and less in low frequency.Among them,the energy proportion with less than 100Hz was very small and its influence could be ignored.In consideration of the natural frequency of underground water-sealed oil storage caverns,no resonance would be caused for the adjacent caverns under excavation blasting.(5)Simulation study on dynamic response characteristics of surrounding rock of adjacent caverns under excavation blasting in underground water-sealed oil storage caverns.Considering the influence of excavation blasting on the dynamic stability of adjacent caverns,according to the space layout and the excavation blasting scheme of the underground oil storage cavern,combining the results of mechanical parameters of rock mass in the research area with the spatial layout of the underground oil depot and the excavation blasting scheme,for different spatial positional relationships and different cavern structures of the Parallel main caverns and crossing water curtain roadways,the three-dimensional numerical model considering the blasting damage of cavern groups in underground water-sealed oil storage was established,and it was verified by comparing field measured data.Then based on the model,the dynamic response characteristics and vibration damage mechanism of adjacent caverns surrounding rock under excavation blasting in underground water-sealed oil storage caverns were analyzed.The results indicated that the middle of the curved wall on the near-blasting side in the typical section of the adjacent main cavern was the unfavorable position for the second layer excavation blasting and the middle of the bottom board in the typical section of the adjacent water curtain roadway was the unfavorable position for expanding excavation blasting.(6)Study on blasting vibration safety criterion for adjacent caverns in underground water-sealed oil storage.Based on the dynamic response characteristics of surrounding rock and the mechanism of vibration damage caused by excavation blasting for the adjacent caverns,according to the theory of stress wave propagation and the dynamic response statistical relationship of the adjacent caverns,the calculation model of blasting vibration safety criterion for adjacent caverns of underground water-sealed oil storage was established respectively.On this basis,combined with the dynamic strength characteristics of surrounding rock of adjacent caverns,the importance correction coefficient was introduced to solve the vibration velocity safety criterion.The results indicated that the critical safety vibration velocity of adjacent main cavern is less than that of the adjacent water curtain roadway.Finally,considering the existing blasting safety regulations in China,the comprehensive safety criterion of blasting vibration velocity of adjacent caverns was proposed to be 12cm/s.